Hydrocarbon gelling process using aluminum soap thickeners with surface active agents



3,539,310 Patented Nov. 10, 1970 Int. Cl. Cl 7/02 US. Cl. 44-7 9 ClaimsThe invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment to us of any royalty thereon.

The invention relates to the thickening of gasoline by aluminum soaps.

Gasoline, thickened or gelled by small quantities (about 1 to 12%) ofaluminum soaps of the higher carboxylic acids, is important as anincendiary in warfare. Various aluminum soaps have been used, the bestknown being napalm, the aluminum soap of a mixture of oleic andnaphthenic acids and coconut oil fatty acids disclosed and claimed inUS. Pat. No. 2,606,107 to Louis F. Fieser. More recently, improvedresults have been obtained by the use of about 0.75 to 4% of aluminumoctoates, notably aluminum hydroxy di-(2-ethyl hexoate) and theisooctoates disclosed in applications, Ser. Nos. 321,747 and 466,242,filed Nov. 20, 1952 and Nov. 1, 1954, respectively, by Leonard Cohen.These applications have ma tured into Pats. 2,741,629 and 2,718,462,respectively.

One advantage of these thickened gasolines over other incendiary fuellies in the fact that they may be produced in the field by mixing thedry soap with gasoline. The proper amount of soap is added to a batch ofgasoline and the mixture agitated until thickening occurs. The gel isthen allowed to stand, or cure, for a certain length of time. During thecuring period the gel develops elasticity.

It is desirable that the time of mixing, or vortex time, and the curetime be as short as possible, particularly to make it possible to usecontinuous rather than batch mixing and prompt use of filled bombs orflamethrowers. It is also desirable that the gel be as high inconsistency as possible for a given amount of thickening agent, that itbe highly elastic, and that it be stable over a long period of time.

We have found that the vortex time and the cure time can be shortenedwhile retaining or enhancing the other desirable qualities by adding tothe gasoline, prior to the r addition of the aluminum soap, a minoramount of nonionic surface-active agent, and that particular improvementcan be obtained by the further addition, together with thesurface-active agent, of certain small amounts of water. The improvementis particularly marked when the soap is aluminum hydroxy di-(2-ethylhexoate).

While we do not wish to be bound by theory, we believe the explanationof the improved results to be as follows. In the process of formation ofaluminum soaps by aqueous metathesis from sodium soap and aluminum saltsin the presence of excess sodium hydroxide, aluminum hydroxide is formedtogether with the aluminum soap. This aluminum hydroxide is hydrophilicin nature and obstructs access of the hydrocarbons to the aluminum soap,thereby retarding gelation. It is believed that the addition ofsurface-active agents containing water causes hydration a hydrophilicgroup which is nonpolar. Suitable hydrophilic groups are hydroxy,polyhydroxy, and polyoxethylene. The hydrocarbon and hydrophilic groupsshould be so balanced that the compound is readily soluble inhydrocarbons in the proportions employed and, for ease in preparing thegel, it is desirable that the compounds be liquid. While the entiregenus of non-ionic surfaceactive agents appears to be usable, we havefound the subgenus consisting of those containing the polyoxyethylenegroup to be definitely superior in that they combine to the highestdegree the various desirable properties set out above.

As stated earlier, we have found that further improvement in the vortextime and cure time is produced by employing water together with thesurface-active agent. While commercial forms of the surface-activeagents frequently contain varying amounts of Water, we have found thatoptimum results are secured by the use of a narrow critical range ofratios of water to agent, extending from 10:90 to 15:85, by weight.

In order to secure mutual solubility of water and agent over a widetemperature range, it has been found desirable to employ a cosolventsuch as isopropanol or the diethyl ether of diethylene glycol. A blendof water, agent, and cosolvent is prepared and then added to thegasoline or other hydrocarbon.

Suitable blends may contain the following ingredients in parts byweight:

Agent: Water: 15 10 Cosolvent: 100

A ratio of ten parts aluminum soap to one part of such a wetting agentblend has proved effective in the preparation of hydrocarbon gelsranging from 0.75 to 4% by weight of aluminum soap.

When all the desired characteristics are taken into accound, two of themost desirable surface-active agents employed to date are:

Trade name: Chemical nature Triton X-45 Octylphenoxypolyethoxy ethanol(average of about 5 ethoxy groups).

Atlas 6-125 6 Polyoxyethylene sorbitol esters of mixed fatty and resinacids (tall oil acids).

The following examples illustrate the improvement attained by use of ourinvention.

EXAMPLE I-(Control) In a laboratory mixer, four percent of aluminumhydroxy di-(Z-ethyl hexoate), which had been formed by reacting aluminumsulfate or aluminum chloride with sodium 2-ethyl-hexoate in an aqueoussolution of sodium hydroxide, was added to gasoline and the electricstirrer rotated at a fixed speed. As the mixture thickens, the level ofthe vortex rises about the rod of the stirrer. The time was noted forthe level to rise from a predetermined initial level to a fixed point onthe rod. This time is used as the vortex time. While the test isempirical in its choice of conditions, it is useful because it gives aquantitative measure of the time a thickener must be mixed in the fieldbefore it is allowed to stand or cure. The cure time was then determinedby allowing the mixture to stand and noting the point at whichelasticity developed.

On a series of tests as described above, the following results weresecured:

Vortex time-2 0 to 40 minutes Cure time- 24 hours Gardner consistencyafter 24 hrs-205 3 EXAMPLE n The tests were repeated a sdescribed inExample I, except that there was first added to the gasoline one part ofa surface-active agent/water/cosolvent blend as described above for eachten parts of aluminum soap, and the soap was then introduced.

In a series of tests, using Atlas G-1256 and Triton X-45 as the agent,the following results were obtained:

Vortex time-less than 3 minutes Cure timeabout minutes Gardnerconsistency after 24 hrs.-65(l to 700 TABLES OF DATA said gasoline anonionic surface active agent selected from the group consisting ofpolyoxyethylene sorbitol esters of mixed tall oil acids,octylphenoxypolyethoxy ethanol and higher fatty acid derivatives ofpolyoxyethylene sorbitan, then adding an aluminum hydroxy soap of atleast one higher carboxyllic acid selected from the group consisting ofhigher fatty acids and mixtures of higher fatty acids and naphthenicacids, the amount of said soap being about one to twelve percent byweight of the gasoline and the amount of surface active agent beingabout five percent by weight of said soap, stirring the mixture ofgasoline, soap and agent until it thickens and finally allowing thethickened mixture to stand until it develops elasticity.

2. A process as defined in claim 1 wherein the surfaceactive agentconsists essentially of a higher fatty acid derivative of polyoxythylenesorbitan.

3. A process as defined in claim 1 wherein said agent-non-ionie] Vortextime,

minutes Trade name Chemical nature (at 77 F.)

(A) Polyoxyethylene sorbitan and sorbitol fatty acid derivatives Tween85 Polyoxyethylene sorbitan trioleate 4. 0 Tween 8l Polyoxyethylenesorbitan monooleate 2. Tween 80. do 3. 0 Tween 65. Polyoxyethylenesorhitan tiistearate 4. 5 Tween Poiyoxyethylene sorbitan monostearate.t. 3. -3 Tween 40. lolyoxyethylene sorbitan monopalmitate 2. 8 Tween 20.a Polyoxyethylene sorbitan monolaurate 3, 5 Atlas G2854. lolyoxyethylenesorbitol tetraoleate. 5. 5 Atlas fir-2855" Polyoxyethylene sorbitolpentaoleate 7. 5

(The preferred agent Atlas G-1256 is closely related to this group) (B)Alkyl polyoxyethylene alcohols 0 0x0 alcohol-4.5 moles ethylene oxide.4. 5

C oxo alcohol6.6 moles ethylene oxide. 8. 9

. Cm 0x0 alcohol-93 moles ethylene oxide- 9. 9

C13 oxo alcohol-3.3 moles ethylene oxide 6. 0

C 3 oxo alcohol5.2 moles ethylene oxide 5. 5

C13 0x0 alcohol-ea. 12 moles ethylene oxide 5. 2

Esso-l53 0 0x0 aleohol 5.9 moles ethylene oxide.-." 7. 1

(C) Alkyl-aryl polyether alcohols Igepal 00-630 Alkyl phenoxypolyoxyethylene ethanol..." 3. 8 Igepal (IA-630.. do 4. 0 Igepal C0430 o4. U Oronite dispersant N I-C. Alkyl phenyl polyethoxyethanol. 3. 5Triton X-l55 Alkyl aryl polyether alcohol 3.8 Triton Xl00 do 3. 8Te1gitol-NPX.. Alkyl phenyl polyethylene glycol ether 2. 8 Tergitol-TMNAlkyl ether of polyethylene glycol 3.0 Tergitol-CW Alkyl aryl polyglyeolothers 2. 7 (The preferred agent Triton X-45 belongs to this group. Itcontains fewer ethoxy groups than the other members and is thereforemore readily soluble in gasoline.)

(D) Aliphatic polyoxyethylene ether type Sterox AJ Aliphaticpolyoxyethylene ether type 3.0 Sterox SE Aliphatic polyoxyethylene thioether. 3. 7 Sterox SK do 4. 0 The following non-ionic agents notbelonging to the preferred subgenus were also found to be operative (E)Sorbitan fatty-acid derivatives Span Sorbitan monooleate 5. 0 Span 60. aSorbitan monostearate 1.8 Span 40-.. Sorbitan monopalmitate. 2. 3 Span20. Sorbitan monolaurate 2. 7 ArlaeeL... Sorbitan sesquioleate 0 (Thesegave satisfactory results, but arefspllids, retguiring a dissolving stepbefore addition 0 e soap.

(F) Higher alcohols Undecanol. Pentadecanol I-Iep tadeeanolsurface-active agent consists essentially of polyoxyethylene sorbitolesters of mixed tall oil acids.

4. A process as defined in claim 1 wherein said surface-active agentconsists essentially of octylphenoxypolyethoxy ethanol having an averageof about five ethoxy groups to the molecule.

5. A process as defined in claim 1 wherein water is added together withsaid agent, the ratio of water to agent ranging from 10:90 to 15:85.

6. A process as defined in claim 2 wherein water is added together withsaid agent, the ratio of water to agent ranging from 10:90 to 15:85.

7. A process as defined in claim 3 wherein water is added together withsaid agent, the ratio of water to agent ranging from 10:90 to 15:85.

8. A process as defined in claim 4 wherein water is added together withsaid agent, the ratio of water to agent ranging from 10:90 to 15:85.

9. A process as defined in claim 1 in which the aluminum soap isaluminum hydroxy di-(2-ethy1 hexoate).

6 References Cited UNITED STATES PATENTS 12/1945 Minich 252-316 12/ 1949Mysels 447 X 8/1952 Fieser 447 9/1955 Cohen 447 FOREIGN PATENTS 4/ 1942Great Britain.

BENJAMIN R. PADGETT, Primary Examiner US. Cl. X.R.

1. A PROCESS OF GELLILNG GASOLINE COMPRISING ADDING TO SAID GASOLINE ANONIONIC SURFACE ACTIVE AGENT SELECTED FROM THE GROUP CONSISTING OFPOLYOXYETHYLENE SORBITOL ESTERS OF MIXED TALL OIL ACIDS,OCTYLPHENOXYPOLYETHOXY ETHANOL AND HIGHER FATTY ACID DERIVATIVESS OFPOLYOXYETHYLENE SORBITRAN, THEN ADDING AN ALUMINUM HYDROXY SOAP OF ATLEAST ONE HIGHER CARBOXYLLIC ACID SELECTED FROM THE GROUP CONSISTING OFHIGHER FATTY ACIDS AND MIXTURES OF HIGHER FATTY ACIDS AND NAPHTHENICACIDS, THE AMOUNT OF SAID SOAP BEING ABOUT ONE TO TWELVE PERCENT BYWEIGHT OF THE GASOLINE AND THE AMOUNT OF SURFACE ACTIVE AGENT BEINGABOUT FIVE PERCENT BY WEIGHT OF SAID SOAP, STIRRING THE MIXTURE OFGASOLINE, SOAP AND AGENT UNTIL IT THICKENS AND FINALLY ALLOWING THETHICKENED MIXTURE TO STAND UNTIL IT DEVELOPS ELASTICITY.